The term "light hydrocarbonaceous liquid" as used herein refers to any hydrocarbonaceous liquid that boils at a temperature below about 1000.degree. F. at atmospheric pressure.
Delayed cokers are used on low value hydrocarbonaceous feeds to obtain higher-value, lower-boiling cracked products. Coking is a high severity thermal cracking or destructive distillation process. It is typically used on vacuum residuum to generate lighter components. In a delayed coker, the hydrocarbonaceous feed is held at an elevated temperature (e.g., about 825.degree. F. to about 925.degree. F.) to deposit coke in the coke drum while cracked vapors containing light hydrocarbonaceous liquids are taken overhead. In general, coking processes that minimize coke yield and maximize light hydrocarbonaceous liquid yield are advantageous.
U.S. Pat. No. 2,271,097 discloses a process for converting high boiling hydrocarbons into lower boiling hydrocarbons. The process includes the step of heating the bottoms from a fractionator in a viscosity breaker at a temperature of 850.degree.-950.degree. F. and a pressure of 75-500 psig.
U.S. Pat. No. 3,172,840 discloses a process for converting hydrocarbonaceous materials such as petroleum oils to gasoline and middle distillates. The process includes the step of cracking a product stream boiling in the range of 750.degree.-950.degree. F. from a coker bubble tower in a thermal cracking furnace at a temperature of 850.degree.-1000.degree. F. and a pressure of 300-1000 psig.
U.S. Pat. No. 4,213,846 discloses a delayed coking process that employs a hydrotreating step wherein gas oil from the coker fractionator is hydrotreated at a temperature of 315.degree.-400.degree. C. (599.degree.-752.degree. F.) and a hydrogen partial pressure of 350-2000 psig.
U.S. Pat. No. 4,519,898 discloses a delayed coking process wherein the oil feed is preheated to a temperature in the range of about 775.degree. F. to about 920.degree. F. and a stripping gas (e.g., steam, nitrogen, normally gaseous hydrocarbons, natural gas) is introduced into the coking drum to form coke containing 5 to 15 weight percent volatile matter.
U.S. Pat. No. 4,547,284 discloses a delayed coking process wherein the feedstock is continuously heated in a coking heater and introduced into a coke drum, the heater is operated to provide a coke drum temperature of from 415.degree.-455.degree. C. (779.degree.-851.degree. F.), and after filling of the drum to the desired level, feedstock introduction is discontinued and the coke drum contents are heated to a temperature of 450.degree.-500.degree. C. (849.degree.-932.degree. F.) and which heating temperature is at least 10.degree. C. (18.degree. F.) greater than the coking temperature, by passing a non-coking vapor (e.g., coker distillate, naphtha, coker gas) through the contents of the drum to reduce the volatile combustible matter content thereof.
U.S. Pat. No. 4,758,329 discloses a delayed coking process wherein the feedstock is an aromatic mineral oil, and the coke CTE is reduced and the coke particle size is increased by sparging with a gas (e.g., nitrogen) during the coking cycle.
U.S. Pat. No. 4,784,746 discloses a process for upgrading crude oil (whole crude or topped crude) by combining the crude oil with a low boiling component that boils below 330.degree. F. and has an aromatic content of at least 20%, then heating the resulting mixture at 400.degree.-500.degree. C. (752.degree.-932.degree. F.) and a pressure sufficient to maintain the feed stream in the liquid phase. The reference discloses pressures in the range of 100-1000 psig. The process is conducted for an effective period of time to increase the proportion of non-residual components in the crude oil using a transalkylation process.
U.S. Pat. No. 4,840,725 discloses a process for converting high boiling hydrocarbons to lower boiling materials characterized by an increase in aromatic content and a lower pour point which comprises contacting said high boiling hydrocarbons with water at a temperature of from about 600.degree. F. to about 875.degree. F. and a pressure of at least about 2000 psig in the absence of any externally supplied catalysts, and wherein the weight ratio of water to high boiling hydrocarbons is from about 0.5:1 to about 1:1, and the water and high boiling hydrocarbon form a substantially single phase system under the elevated temperature and pressure conditions used.